New specificities of the HLA-DRw system will be searched for by cross-absorption procedures involving duo or tri-specific antisera, and using bulk-cultured previously typed and selected lymphoblastoid cell lines. Reactivities of the sera with donor cells from caucasian, black, oriental, Navajo Indian, and South America Indian subjects will be determined. Dysequilibrium of the HLA system in certain diseases will be investigated: particularly, HLA in Myasthenia Gravis in relation to titers of acetylcholine receptor autoantibodies; HLA in Jacob Creutzfeldt disease, and a large series of Alzheimer's patients will be determined. Further quantitative studies will concern cell alloantigen representation on leukemic cells, including chronic lymphatic, acute lymphatic, acute myeloid, and "hairy" cell leukemia.